Slack belt rotation sensor

ABSTRACT

A shaft rotation sensing device wherein an idler shaft is coupled to an input shaft through a flexible belt. Friction bearing means provide a low level of resistance rotation of the idler shaft for maintaining one segment of the belt taut under constant speed conditions while a flywheel coupled to the idler shaft through a lost motion connection responds to shaft acceleration for tensioning the belt segment and shaft deceleration for slackening the belt segment. Lateral displacement of belt is detected for sensing shaft rotation. Combined with a clockwork mechanism, the rotation sensor forms part of an antitheft device for computing registers.

[451 Jan. 25, 1972 Bumpus, Jr. et al.

3,l2l,53l 2/1964 235/58? 3,319,256 5/1967Valerio....................................346/43 [54] SLACKBELTROTATION SENSOR [72] Inventor: Fredrick T- Gutmann, Caldwell, NJ.

Primary Examiner-Stephen J. Tomsky [73] Assignee: Lockheed AircraftCorporation, Burbank,

Calif.

AttorneyBilly G. Corber and George C.; Sullivan ABSTRACT A shaftrotation sensing device wherein an idler shaft is cou- 22' Filed: Feb.4, 1970 [21] Appl. No.: 8,516

pled to an input shaft through a flexible belt. Friction bearing meansprovide a low level of resistance rotation of the idler G04, shaft formaintaining one segment of the belt taut under con- 235; P 58 Z 91 D 94stant speed conditions while a flywheel coupled to the idler 58/145 4465: 33/132 74/242 shaft through a lost motion connection responds toshaft ac- 51 lnt.Cl............... 5s FieldofSearch...............

celeration for tensioning the belt segment and shaft deceleration forslackening the belt segment. Lateral displacement of belt is detectedfor sensing shaft rotation. Combined with a References Cited V clockworkmechanism, the rotation sensor forms part of an UNITED STATES PATENTSantitheft device for computing registers.

.74/242 9 x 4 Claims, 2 Drawing Figures liqlifii l-x.

PAIENIED M25 I972 SHEET 2 0F 2 INi/fNTOR, FREDRICK I GUTMANN AttorneySLACK BELT ROTATION SENSOR BACKGROUND OF THE INVENTION This inventionrelates generally to rotation sensors and more particularly to antitheftdevices for use with computing registers of the typedisclosed in U.S.Pat. No. 3,121,531 to provide a sensory indication on a recording sheetwhen the alloted downtime of the register has been exceeded.

Computing registers of the type disclosed in U.S. Pat. No. 3,121,531 arecommonly used in conjunction with a pump and a liquid meter as part of aliquid fuel delivery system on tank trucks and the like. In suchapplications, the computing register functions'to compute and to printout on a recording sheet information such as quantity, unit price, totaltax, total sales price, including tax and/or discount where applicablefor accounting and customer billing purposes. Before starting thedelivery, the driver inserts a ticket into the computing register. Hethen rotates a control knob which causes the computing register toperforms several functions: capture the ticket so that it cannot bewithdrawn until the transaction is complete, reset the print and displaywheels to zero, print zeros in the gallon and money columns of thedelivery ticket, and reposition the ticket for printout of deliverydata. After this initialization, delivery can start. At completion ofdelivery, the driver rotates the computing register control knob againand this action causes the register to imprint on the ticket the numberof gallons delivered and the price, returns the ticket to its originalposition in the register, and then releases the ticket.

With such a computing register, it is possible for the operator toinsert the ticket, start a delivery to an unauthorized receiver, shutofl the pump, leave the ticket in the register, and then proceed to alegitimate customer. ,There he can resume delivery and the customer willreceive a ticket which shows an amount larger than that delivered tohim. This practice is sometimes referred to as riding the ticket SUMMARYOF THE INVENTION An object of this invention is to prevent this type ofcheating by providing an antitheft device which will operate to indicateon the ticket if a delivery has been interrupted for a period exceedinga predetermined amount of time-say minutes, for example.

Another object of this invention is to provide a mechanical rotationsensor for detecting both shaft acceleration and shaft deceleration.

The antitheft device includes a clockwork which is wound by rotating thecontrol knob of the computing register via suitable gearing. Aninterposer is associated with the clock in such a manner that it will bewithdrawn when the predetermined period has elapsed whereby the finalprintout operation will indicate on the ticket that the prescribeddelivery period has been exceeded.

The purpose of the rotation sensor is to stop the clockwork while actualdelivery takes place. In the computing register there is an input shaftdirectly connected to the pump driven meter. Coupled to this input shafteither directly or by suitable gearing is a sprocket on a horizontalshaft which drives a flexible belt, such as a slack ladder or rollerchain. Keyed to the driven sprocket is an idler shaft and a drive hub. Aflywheel is rotatably mounted on the idler shaft and coupled to thedrive hub through a lost motion mechanism, allowing limited rotation ofthe flywheel relative to the drive hub. A follower wheel attached to apivoted follower arm rides on top of the flexible belt intermediate thedriving and driven sprockets. The follower arm is so designed that itstops the clockwork when it is in the up position-that is, when theupper portion or segmentof the flexible belt is taut.

Rotation of the input shaft for the flexible belt tends to tensi on theupper segment of thebelt, and this is augmented by the limited lag ofthe flywheel. Thus, when the meter is running, the idler arm is up andstops the clock motion. When the meter stops, the drive sprocket stops,but the energy stored in the flywheel tends to keep the driven sprocketgoing,

thereby slackening the upper segment of the belt. This drops thefollower arm and allows the clock to run.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an isometric view of therotation sensor; and

FIG. 2 is an isometric view showing schematically the antitheftclockwork mechanism controlled by the rotation sensor.

Like numerals refer to like parts in these two figures of the drawing.

I DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, therotation sensor includes a horizontal input shaft 10 which is coupled toand actuated by a pumpdriven fluid meter 15. Driver sprocket wheel 11 issecured to shaft 10 and drives a second sprocket wheel 12 through aloosely draped flexible belt such as a slack ladder or roller chain belt13. Preferably, the second or driven sprocket 12 is at least 50 percentsmaller than the drive sprocket. Keyed to driven sprocket 12 is an idlershaft 14 supported for rotation in suitable friction bearings 16.Bearings 16 exert sufficient resistance of shaft 14 to rotation that theupper segment 17 of belt 13 will be maintained taut during periods ofrotation of input shaft 10.

Secured to idler shaft 14 is a drive hub 18 having a pin 19 projectingradially outward therefrom. Adjacent hub 18 is a flywheel 20 rotatablysupported on shaft 14. Two pins 21 and 22 project axially from theflywheel and are spaced apart sufficiently to cooperate with pin 19 ondrive hub 18 and allow limited rotation of flywheel 20 relative to hub18 and idler shaft 14. It has been found that approximately relativerotation between the flywheel and hub is best for achieving minimumhunting and positive tensioning and slackening of the upper segment 17of belt 13 on acceleration and deceleration, respectively, of inputshaft 10 when operating at about 70 to revolutions per minute. At otherspeed ranges, something other than 90 of lost motion may be desirablefor the flywheel.

A follower wheel 87 attached to one end of an arm 51 rides on top ofbelt 13. As shown in the drawing, arm 51 is pivoted intermediate itsends at 52 to the machine frame. A link 88 connected to the free end 49of arm 51 is lifted when the upper segment 17 of belt 13 goes slack andlowered when the belt is drawn taut. This link is employed in theantitheft system as a control lever for the timing mechanism ashereinafter described.

Referring to FIG. 2, shaft 54 is connected to the reset con trols of acomputing register, such as that shown and described in US. Pat. No.3,121,531. Before delivery, the driver manually turns a control knob onthe computing register which conditions the computer register and causesshaft 54 to rotate about 380 counterclockwise to initialize theantitheft mechanism.

Rotation of shaft 54 is transmitted to clockwork 55 via compound gear56, split gears 57 and 58, idlers 59 and 60, input gear 61 and slipclutch 62. The winding of the clockwork takes place in direction 63. Asthe clockwork is wound, the detent 64 of pivoting lever 65 rides up oncam 66, urging the interposer 67 to the right, until it engages latch68. The vertical motion of latch 68 will be described later.

A suitable clockwork is made by M. H. Rhodes, Inc. of

Hartford, Conn. It is designated as Mark-Time 1900 series,

one model of which rotates through in 10 minutes. Cam 66 and lever 65are part of this clockwork.

The clockwork has internal stops (not shown) which limit winding to nomore than about 180 from the point where detent 64 drops into depression70 of cam 66.

Once clockwork 55 is wound, it will tend to run backwards(counterclockwise) in direction 69 until detent 64 of pivoting lever 65drops into depression 70 of cam 66. It will also drive gears 58 via slipclutch 62 and gears 61, 60 and 59. Gears 57 and 58 are interconnected bymeans of a one-way mechanism so that the clockwork is free to run downwithout having to rotate shaft 54. Fastened to gear 58 is ratchet wheel71. Gear 57 carries a pivot 72 for pawl 73 which is urged into contactwith the ratchet wheel by spring 74 which is also carried by gear 57.The gear train is so proportioned that for the 180? input rotation intothe clockwork, gear 58 rotates about 300?. When the clockwork is fullywound, the tail of pawl 73 moves into pin 75 which is stationary in themachine frame. The pawl is now disengaged from the sprocket wheel, andgear 58 is free to turn clockwise. The computing register is so designedthat before the next winding cycle, shaft 54 is rotated clockwise,moving pawl 73 away from stop pin 75. When gear 57 again rotatesclockwise during the next winding cycle, pawl 73 will again engageratchet wheel 7 1.

If the clockwise has run down only part of the way, a full winding cyclewould overpower one of its internal stops. Overwinding is prevented bythe slip clutch 62.

Consider now the conditions where the clockwork 55 has run down, androtation of cam 66 has reached its end. Detent 64 has dropped intodepression 70, and the interposer 67 has moved to the left. Now latch68, urged by extension spring 76, moves upwards, and bell crank 77rotates counterclockwise about pivot 78 which is fixed in the machineframe. This action moves lever am 79 to the left, placing shutter 80over print wheel 48. This is preferably a print wheel indicating priceper gallon, so that this action does not obscure gallon or dollarprintout. When the amount delivered is imprinted on the ticket, withonly the price per gallon figures being altered by omission of a digitin a characteristic fashion, a delivery of excess downtime duration isclearly indicated. This type of sensory indication by omission of adigit is considered superior to one such as where the ticket ispunctured, since the driver might in the latter case insert a shim toprevent puncture.

Latch 68 must be guided, as may be done by pins 81 fixed in the frameand riding in slots 82. Also, latch 68 must be reset before the nextdelivery cycle starts. This may be effected by a roller 83 fixed in andmoving with the ticket carriage in directions 92 and 84. When thecarriage, during initialization of the computing register, moves indirection 92, the roller 83 rides over cam surface 85, depressing latch68. Detent 86 of the latch is suitably pivoted and spring loaded to rideover interposer 67 on the downstroke.

Roller 83 is kept out of contact with cam 85 on the output print cycleuntil the carriage returns in direction 84 sufficiently to preventpremature resetting latch 68.

Finally, reference is again made to the function of the rotation sensorin this system. While the meter runs, the upper segment of flexible belt13 on which follower wheel 87 rides, is taut, and urges the follower 51upwardly in direction 53. This action lowers link 88. Thus, arm 89 whichpivots on pin 90 fixed in the frame, rotates clockwise, turning crank 91counterclockwise. Inside the clockwork an extension of this crank (notshown) engages the escapement wheel and thus stops the clockwork. Whenthe belt becomes slack, arm 51 drops, and the linkage consisting of link88, arm 89 and crank 91 disengages itself, allowing the clockwork toresume running. If the downtime of the computing register exceeds theallowable time established by the clock, shutter is moved over printwheel 48 by operation of the described linkage mechanism to obscure theprintout and thereby provide an indication of the excessive downtime.

While the rotation is described herein in conjunction with an antitheftsystem for computing registers, it should be recognized that the devicehas utility beyond this specific use wherever changes in shaft rotationare to be monitored.

I claim:

1. A rotation sensor comprising, an idler shaft, a wheel secured to saididler shaft, a drive shaft, a flexible belt coupling said wheel to saiddrive shaft, the rotation of which is to be sensed, friction bearingmeans supporting said idler shaft, a flywheel generally coaxiallyaligned with said idler shaft and coupled thereto for limited relativeangular rotation,

saidflywheel providin inertia forces normally exceeding the fnctronloads exerted y said bearing means, follower means engaging saidflexible belt intermediate said wheel and said drive shaft for sensinglateral displacement of said belt, a timer mechanism responsive to saidfollower means for accumulating intervals of time in which said driveshaft is stationary, and

1. A rotation sensor comprising, an idler shaft, a wheel secured to saididler shaft, a drive shaft, a flexible belt coupling said wheel to saiddrive shaft, the rotation of which is to be sensed, friction bearingmeans supporting said idler shaft, a flywheel generally coaxiallyaligned with said idler shaft and coupled thereto for limited relativeangular rotation, said flywheel providing inertia forces normallyexceeding the friction loads exerted by said bearing means, followermeans engaging said flexible belt intermediate said wheel and said driveshaft for sensing lateral displacement of said belt, a timer mechanismresponsive to said follower means for accumulating intervals of time inwhich said drive shaft is stationary, and arm means responsive to saidtimer mechanism for indicating completion of a predeterminedaccumulation of said intervals of time.
 2. A device as defined in claim1 wherein said timer mechanism is resettable.
 3. A device as defined inclaim 2 wherein said arm means is a mechanical link movable to provide asensory indication that the predetermined accumulation of said intervalsof time has been exceeded.
 4. A device as defined in claim 3 including ashutter coupled to said mechanical link.